Adhemerval Zanella d40ac01cbb stdlib: Make abort/_Exit AS-safe (BZ 26275) ... The recursive lock used on abort does not synchronize with a new process creation (either by fork-like interfaces or posix_spawn ones), nor it is reinitialized after fork(). Also, the SIGABRT unblock before raise() shows another race condition, where a fork or posix_spawn() call by another thread, just after the recursive lock release and before the SIGABRT signal, might create programs with a non-expected signal mask. With the default option (without POSIX_SPAWN_SETSIGDEF), the process can see SIG_DFL for SIGABRT, where it should be SIG_IGN. To fix the AS-safe, raise() does not change the process signal mask, and an AS-safe lock is used if a SIGABRT is installed or the process is blocked or ignored. With the signal mask change removal, there is no need to use a recursive loc. The lock is also taken on both _Fork() and posix_spawn(), to avoid the spawn process to see the abort handler as SIG_DFL. A read-write lock is used to avoid serialize _Fork and posix_spawn execution. Both sigaction (SIGABRT) and abort() requires to lock as writer (since both change the disposition). The fallback is also simplified: there is no need to use a loop of ABORT_INSTRUCTION after _exit() (if the syscall does not terminate the process, the system is broken). The proposed fix changes how setjmp works on a SIGABRT handler, where glibc does not save the signal mask. So usage like the below will now always abort. static volatile int chk_fail_ok; static jmp_buf chk_fail_buf; static void handler (int sig) { if (chk_fail_ok) { chk_fail_ok = 0; longjmp (chk_fail_buf, 1); } else _exit (127); } [...] signal (SIGABRT, handler); [....] chk_fail_ok = 1; if (! setjmp (chk_fail_buf)) { // Something that can calls abort, like a failed fortify function. chk_fail_ok = 0; printf ("FAIL\n"); } Such cases will need to use sigsetjmp instead. The _dl_start_profile calls sigaction through _profil, and to avoid pulling abort() on loader the call is replaced with __libc_sigaction. Checked on x86_64-linux-gnu and aarch64-linux-gnu. Reviewed-by: DJ Delorie <dj@redhat.com>		2024-10-08 14:40:12 -03:00
..
types
argp-ldbl.h
atomic_wide_counter.h
cmathcalls.h
cpu-set.h
dl_find_object.h
dlfcn.h
endian.h
err-ldbl.h
error-ldbl.h
error.h
fcntl2.h
getopt_core.h
getopt_ext.h
getopt_posix.h
locale.h
mathcalls-helper-functions.h
mathcalls-narrow.h
mathcalls.h
monetary-ldbl.h
mqueue2.h
poll2.h
posix1_lim.h
posix2_lim.h
printf-ldbl.h
select2.h
select-decl.h
setjmp2.h
sigstack.h
sigstksz.h
socket2.h
stab.def
statx-generic.h
statx.h
stdio2-decl.h
stdio2.h
stdio-ldbl.h
stdio.h
stdlib-float.h
stdlib-ldbl.h
stdlib.h
string2.h
string_fortified.h
strings_fortified.h
syslog-decl.h
syslog-ldbl.h
syslog.h
types.h
unistd_ext.h
unistd-decl.h
unistd.h
wchar2-decl.h
wchar2.h
wchar-ldbl.h
wctype-wchar.h
xopen_lim.h